The proposal is for predoctoral training for Rhiannon Luyster, currently a second year graduate student in developmental psychology and a member of the Development, Psychopathology and Mental Health certificate program at the University of Michigan. The research plan is for a cross-sectional study of the very early stages of language comprehension in young children with autistic spectrum disorders (ASD), other developmental delays and typical development. Three quasi-natural tasks will be used to contrast cognitive and social explanatory theories concerning processes in early language learning: a task measuring children's use of social cues mapping new labels, a task assessing the role of mutual exclusivity constraints on "fast-mapping" of new words, and a task that assesses children's generalization of new words. Children's performance on these tasks will be related to other measures of social skills, cognitive ability and communication. Understanding the components of early comprehension in children with ASD and language-related delays will have direct implications for interventions and may be useful to eventual neurobiological models of the information-processing deficits that underlie autism and language disorder.